SEC FORM 4

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

KANIA EDWIN M JR

(Last)

(First)

(Middle)

C/O FLAGSHIP VENTURES

1 MEMORIAL DRIVE

(Street)

CAMBRIDGE

02142

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
ACCELERON PHARMA INC [ XLRN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
09/24/2013

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	09/24/2013		C		1,376,249	A	⁽¹⁾	1,381,116	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Common Stock	09/24/2013		C		507,666	A	⁽¹⁾	1,888,782	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Common Stock	09/24/2013		C		293,144	A	⁽¹⁾	2,181,926	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Common Stock	09/24/2013		C		39,175	A	⁽¹⁾	2,221,101	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Common Stock	09/24/2013		C		60,245	A	⁽¹⁾	2,281,346	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Series A Convertible Preferred Stock	⁽¹⁾	09/24/2013		C			1,376,249	⁽¹⁾	⁽¹⁾	Common Stock	1,376,249	$0	0	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Series B Convertible Preferred Stock	⁽¹⁾	09/24/2013		C			507,666	⁽¹⁾	⁽¹⁾	Common Stock	507,666	$0	0	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Series C Convertible Preferred Stock	⁽¹⁾	09/24/2013		C			293,144	⁽¹⁾	⁽¹⁾	Common Stock	293,144	$0	0	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Series D Convertible Preferred Stock	⁽¹⁾	09/24/2013		C			39,175	⁽¹⁾	⁽¹⁾	Common Stock	39,175	$0	0	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾
Series F Convertible Preferred Stock	⁽¹⁾	09/24/2013		C			60,245	⁽¹⁾	⁽¹⁾	Common Stock	60,245	$0	0	I	See Footnotes⁽²⁾⁽³⁾⁽⁴⁾⁽⁵⁾

Explanation of Responses:

1. Upon closing of the Issuers initial public offering, each share of Series A, B, C, D and F Convertible Preferred Stock automatically converted into one share of Common Stock without payment of further consideration. The shares had no expiration date.

2. 1,297,803 shares of Series A Convertible Preferred Stock, 478,729 shares of Series B Convertible Preferred Stock, 276,435 shares of Series C Convertible Preferred Stock, 36,942 shares of Series D Convertible Preferred Stock, and 56,811 shares of Series F Convertible Preferred Stock of the issuer were owned directly by Applied Genomic Technology Capital Fund, L.P. (AGTC Fund). After the conversions listed herein AGTC Fund owns 2,146,720 shares of common stock.

3. NewcoGen Group, Inc. (NewcoGen Inc.) is the general partner of AGTC Partners, L.P., which is the general partner of AGTC Fund. NewcoGen Inc. is a wholly-owned subsidiary of Flagship Ventures Management, Inc. Noubar B. Afeyan Ph.D. and Edwin M. Kania, Jr. are the directors of Flagship Venture Management, Inc. and may be deemed to have beneficial ownership with respect to all shares held by AGTC Fund. Each of Mr. Kania and Dr. Afeyan disclaim beneficial ownership over such shares held by AGTC Fund except to the extent of their pecuniary interest therein. Mr. Kania holds 4,867 shares of the issuers common stock directly.

4. 78,446 shares of Series A Convertible Preferred Stock, 28,937 shares of Series B Convertible Preferred Stock, 16,709 shares of Series C Convertible Preferred Stock, 2,233 shares of Series D Convertible Preferred Stock, and 3,434 shares of Series F Convertible Preferred Stock of the issuer were owned directly by AGTC Advisors Fund, L.P. (AGTC). After the conversions listed herein AGTC owns 129,759 shares of common stock.

5. NewcoGen Inc., is the general partner of AGTC Partners, L.P., which is the general partner of AGTC. NewcoGen Inc. is a wholly-owned subsidiary of Flagship Ventures Management, Inc. Noubar B. Afeyan Ph.D. and Edwin M. Kania, Jr. are the directors of Flagship Venture Management, Inc. and may be deemed to have beneficial ownership with respect to all shares held by AGTC. Each of Mr. Kania and Dr. Afeyan disclaim beneficial ownership over such shares held by AGTC except to the extent of their pecuniary interest therein. Mr. Kania holds 4,867 shares of the issuers common stock directly.

	/s/ Kevin F. McLaughlin, attorney in fact for Edwin M. Kania, Jr.	09/26/2013
	** Signature of Reporting Person	Date
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